Abstract
The use of biobased substances derived from industrial and household waste as renewable raw materials for environmental applications is gaining prominence due to its sustainable and cost-effective approach to waste valorisation. Herein, we report the uptake of paraquat, a widely used pesticide, by magnetite nanoparticles coated with composted urban biowaste-derived substances (MNP-BBS). The magnetic nanoparticles were prepared using a modified co-precipitation method, and were characterized through various physicochemical techniques. They were tested as an adsorbent for paraquat removal under diverse experimental conditions, exploring the influence of pH (3−10), MNP-BBS dosages (200−1000 mg L−1), ionic strength (0−0.01 M), and presence of organic matter. The kinetic study revealed that the adsorption of paraquat onto MNP-BBS follows the pseudo-second-order model, reaching the adsorption equilibrium after 2 h of contact and 90% of paraquat removal in the best condition tested (1000 mg L−1). The equilibrium experimental data showed a high adsorption performance with a good fitting to the Freundlich isotherm model. Also, from Langmuir model a maximum adsorption capacity of 0.085 mmol g−1 was estimated. The results indicated that electrostatic interaction between the negative functional groups of the adsorbent and the paraquat play a major role in the adsorption mechanism, although the contribution of π-π and hydrophobic interactions cannot be completely ruled out. This research underscores the potential of utilizing MNP-BBS as an effective adsorbent for the removal of paraquat, shedding light on its application in sustainable water purification processes.